Geminiano Montanari

Geminiano Montanari (June 1, 1633 – October 13, 1687) was an Italianastronomer, lens-maker, and proponent of the experimental approach to science.

He is best known for his observation, made around 1667, that the second brightest star (called Algol as derived from its name in Arabic) in the constellation of Perseus varied in brightness. It is likely that others had observed this effect before, but Montanari was the first named astronomer to record it. The star's names in Arabic, Hebrew and other languages, all of which have a meaning of "ghoul" or "demon", imply that its unusual behaviour had long been recognised.

Montanari's observations of the great comet of 1680 are mentioned twice in the third volume of Newton's Principia.

In 1679 Montanari moved to a teaching post in Padua, but almost all records of this period of his life have been lost. A letter survives from 1682 recording a sighting of Halley's Comet. He also wrote on economics, observing that demand for a particular commodity was fixed, and making comments on coinage and the value of money (1683).